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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

A Combined Study of the Pion's Static Properties and form Factors

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El-Bennich, B. [1, 2] ; de Melo, J. P. B. C. [2] ; Frederico, T.
Total Authors: 3
[1] Univ Estadual Paulista, Inst Fis Teor, BR-01140070 Sao Paulo - Brazil
[2] Univ Cruzeiro Sul, Lab Fis Teor & Computac, BR-01506000 Sao Paulo - Brazil
Total Affiliations: 2
Document type: Journal article
Source: FEW-BODY SYSTEMS; v. 54, n. 11, p. 1851-1863, NOV 2013.
Web of Science Citations: 20

We study consistently the pion's static observables and the elastic and gamma{*} gamma -> pi (0) transition form factors within a light-front model. Consistency requires that all calculations are performed within a given model with the same and single adjusted length or mass-scale parameter of the associated pion bound-state wave function. Our results agree well with all extent data including recent Belle data on the gamma{*} gamma -> pi (0) form factor at large q (2), yet the BaBar data on this transition form factor resists a sensible comparison. We relax the initial constraint on the bound-state wave function and show the BaBar data can partially be accommodated. This, however, comes at the cost of a hard elastic form factor not in agreement with experiment. Moreover, the pion charge radius is about 40 % smaller than its experimentally determined value. It is argued that a decreasing charge radius produces an ever harder form factor with a bound-state amplitude difficultly reconcilable with soft QCD. We also discuss why vector dominance type models for the photon-quark vertex, based on analyticity and crossing symmetry, are unlikely to reproduce the litigious transition form factor data. (AU)

FAPESP's process: 09/51296-1 - Hadronic effects in heavy-quark physics
Grantee:Bruno Omar El-Bennich
Support type: Research Grants - Young Investigators Grants
FAPESP's process: 10/05772-3 - Hadronic effects in heavy-quark physics
Grantee:Bruno Omar El-Bennich
Support type: Scholarships in Brazil - Young Researchers
FAPESP's process: 09/00069-5 - Few-body aspects of many-body physics
Grantee:Tobias Frederico
Support type: Research Projects - Thematic Grants